The reliable container for your data.

Panzerschrank leverages the power of ES2015+ to bring you an effortless way to help you deal with your objects literals.

Frankly speaking - out of sheer boredom.

There is one more reason, though.

Well, I haven't any tool fullfiling my requirements that are as follow:

1. simple to use,
2. lightweight,
3. extensive object literals (described below)

What I needed is basically to have a possibility to unfreeze a frozen object. Unfreezing means I want to have a possibility to add new or modify existing properties Is there any way to prevent mutation to happen? There are

• Object.seal
• Object.freeze
• Object.preventExtensions functions available, however none of them matches my needs.

Install Panzerschrank to your project...

yarn add panzerschrank

...then use it like so:

import vault from 'panzerschrank/sloppy';
const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });

or

import vault from 'panzerschrank/strict';
const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });

Vault uses proxy under the hood, therefore it intercepts property access. Basically it works like a normal object with quite a few gotchas, though. The key differences are:

1. In case of non-primitive, you receive a new instance of given object on each get.
2. Adding/modifying property is changed.
3. Vault is iterable.
4. You are not able to list keys - this is intentional, but may be changed in future.

const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });
safeObj.numbers; // [0, 1, 2], but...
safeObj.numbers !== safeObj.numbers; // === true
safeObj.numbers.pop(); // === 2
safeObj.numbers.pop(); // === 2
safeObj.numbers.length; // === 3

Adding a new property or modifying an existing one is easy...

const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });
safeObj(obj => {
  obj.numbers = 'hey, i am string now!';
});
safeObj.numbers; // === 'hey, i am string now!'

To avoid the leak of object, the passed function is sandboxed, meaning you can't accept anything but its own scope.

const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });
const str = '2234';
safeObj(obj => {
  obj.numbers = str; // throws ReferenceError;
});

however, safeObj accepts extra arguments :)

const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });
safeObj((obj, str) => {
  obj.numbers = str;
}, '2234');
safeObj.numbers; // === '2234'

This is the only way to do it. Setting property in a normal way simply won't work.

const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });
safeObj.numbers = 2; // throws exception or does nothing

const safeObj = vault({ foo: 'bar', numbers: [0, 1, 2] });
for (const [key, value] of safeObj) {
  console.log(key, value); // prints foo, bar and then numbers and [0, 1, 2];
}

GPLv3